Light source



Oct. 6, 1959 w. F. KAZUK 2,907,909

LIGHT SOURCE Filed July 5, 1957 2 Sheets-Sheet 1 y HEATTSRY 32 2 2e/CATHODE ALQJDE 46 Fig INVENTOR. WALTER FRANK KAZUK ATTORNEYS Oct. 6,1959 V w, KAZUK 2,907,909

LIGHT SOURCE Filed July 5, 1957 2 Sheets-Sheet 2 TO CATHODE Fig. 4

INVENTQR. WALTER FRANK KAZ UK BY a W ATTORNEYS a phosphor which LIGHTSOURCE Walter Frank Kazuk, Preakness, N.J., assignor to Allen B. Du MontLaboratories, Inc., Clifton, N.J., a corporation of Delaware ApplicationJuly 5, 1957, Serial No. 670,160 20 Claims. (Cl. 313-109) This inventionrelates to light sources and particularly to a device for emittingbrightly luminous light which may be modulated, pulsed on and oif, orhave its spectral composition varied.

In the past, some light sources such as strobe-lights have employedgaseous devices for the production of pulses of light. Performance ofthese devices has been limited by the enclosed gas characteristics, suchas ionization and discharge properties at predetermined voltage levels.Generally, the response has been restricted to pulses within acomparatively low range of frequencies and continuous modulation of thelight beam could not be obtained.

Other light sources have made use of plates coated with produced lightwhen bombarded by electrons emitted from a cathode. These light sourcesutilized conventional cathode ray tube type structures, wherein a smallcathode was placed in a transverse plane at one end of a tube envelope,and a phosphor coated faceplate and anode were located at the targetend. Ordinarily, the impinging electrons caused light transmissiondirectly through a glass faceplate which Was coated with phosphor.Special tubes have utilized an opaque reflecting faceplate or anodepositioned at one end of a cylindrical glass envelope. The phosphorcoated anode was placed at an angle to the longitudinal axis of thetube, presenting an elliptical configuration. The electron beambombarded the phosphors which projected light at an angle to the tubeaxis, through the glass cylinder Wall. The size of the cathode and anodein these arrangements have had practical limitations resulting incomparatively small light output. Where desired, a control gridpositioned in close proximity to the transverse cathode suppliesmodulating signals to vary the duration, intensity, and/ or frequency ofthe electron emission, and the resulting light.

' It is therefore the principal object of the present invention .toprovide a novel light source.

' It is another object of the invention to provide an improved structurefor a light source capable of developing high luminosity.

,An additional object of the invention is to provide a novelconfiguration which permits greater control over the duration,intensity, and frequency of the light source.

A further object is to provide a light source having an improvedmodulation frequency response.

Still another object is to furnish a source of visible or invisiblelight capable of emitting and controlling a multiple number of separateradiations, simultaneously or in sequence.

According to the present invention a light source utilizing a cathoderay tube type structure permits the attainment of increased lightoutputs. A cylindrical cathode and grid,and,an anode are arrangedconcentrically to provide maximum, usable surface areas. Electrons areemitted radially by a longitudinally positioned tubular cathode and passthrough a control grid which encircles the length of the cathode. Thestream of electrons strikes I large coated surface area whichluminosity, while the tubular cathode supplies the large 2,907,909Patented Oct. 6, 1959,

a phosphor coated inner surface of a cylindrical or conical anode, whichmay be an integral part of a glass or metal outer shell. Light emittedby the phosphors is projected through a transparent glass faceplatewhich forms the front end or side of the enclosure. The anode supplies acan emit light of high number of electrons that are necessary. Thecontrol grid and phosphor coating may be divided into several sections,permitting independent outputs or combinations of various forms of lightemission.

The detailed description and accompanying drawings which follow considerthe device in several particular configurations. It is to be understoodthat these embodiments are chosen for the purpose of explanation andillustration and are not to be construed as defining the limits of theinvention. The term light as used herein is assumed to include visibleluminous energy as well as invisible radiations suchas ultraviolet andinfrared.

Fig. 1 represents a view of one embodiment of the invention utilizing aconical structure. In this view part of the envelope is removed, showingthe location of thevarious components and a longitudinal arrangement ofmultiple grid and phosphor sections;

Fig. 2 indicates a radial arrangement of multiple grid and phosphorsections;

Fig. 3 shows a cylindrical configuration Which emits light in atransverse plane through a longitudinal transparent faceplate; and

Fig.4 illustrates a structural variation of a controlgr'id and an addedaccelerating grid which can be used to control the flow of electronsemitted by the cathode.

As shown in Fig. 1, a conical or funnel shaped glassstructure 10 formsthe outer shell or, envelope of the device, with a transparent faceplate12 completing the enclosure. The entire inner surface of the funnel iscoated with a first layer of conductive metallic material forming ananode 14 and a second layer of phosphorescent material. 'Ihe phosphorcoating may be applied homo geneous to cover the full surface ofstructure 10. Alternatively, separate phosphor coatings 16, 18 and 20,each having difierent light emission properties, may be applied 1 totruncated cone-like areas formed by dividing structure 10 longitudinallyinto separate peripheral strips or sections.

A hollow cylindrical cathode Q2, having an electron emissive layer 24 onthe outer surface, is positioned along the longitudinal axis of thedevice and extends for substantially its full length. Electron emissionmay be produced in any suitable manner, such as by use of heaterfilament wires 26, placed in the hollow cathode center or with anemissive coated heater utilized directly without a cathode structure.

Surrounding the cathode are separate Wire mesh control grids 28, 30 and32, which control electron emission to phosphor sections 16, 13 and 20,respectively. Alter-' natively, a single control grid encircling thecathode for substantially its full length may be utilized in conjunctionwith a single homogeneous phosphor coating on the tural support forseveral components. Another variation of the device utilizes a cap overthe open end of the,

cathode to provide added support for the grid and cath ode'structuresand to shield the center heater filaments from view. Battery 46represents a voltage potential supplied between cathode 22 and anode 14.

The description of the operation of the instant device may first beconfined to one of the several sections illustrated. The cathode 22takes the form of a long hollow cylinder with heater filaments 26running through the center. The filament wires 26 heat the cylindercausing copious electron'emission along the en.- tire length of theelectrode surface which is coated with emissive layer 24. Anelectrostatic field between anode 14 and cathode 22 is established bybattery 46, causing the electrons to follow a radial path, passingthrough the interposed control grid.

The grid impresses signal voltages or pulses of varying frequency,duration and/or amplitude. The signal voltage amplitude variationcontrols the intensity of electron emission. A sutficiently negativecontrol voltage can halt the flow. The potential field produced bybattery 46, which places a positive charge on anode 14 with respectiveto the negative cathode 22, attracts the modulated stream of electronsto the anode where they are collected. During the process of traveltoward the anode, the electron stream impinges upon the phosphor coatingcausing emission of light. The angular position of the conical surfacedirects the light through the transparent faceplate 12, with themetallic reflective layer forming anode l4 contributing additionallight.

The operation of each longitudinal section shown in Fig. l is the same,with partition plates 34 and 36 preventing electron emission in oneportion from activating phosphors in another area. The sectionalizedarrangement illustrated is particularly suitable for providing lightwhose color depends upon the signals applied to control grids 28, 3t and32, which activate separate colored phosphors 16, 18 and 20. Controlvoltages may be used to combine various colors to give a particularoutput hue by varying the intensity of each color component. Forexample, a combination of red, blue and green phosphors would appear tothe eye at a distance to be a certain resultant color. The particularshade of the color would depend upon the intensity of signal applied toeach individual phosphor. Special phosphors may also be utilized whichemit invisible infrared or ultraviolet light.

Commutation or switching systems known in the art may be employed tooperate the various grids simultaneously, sequentially, or independentlyto activate the particular phosphors and project a wide variety ofuseful signals, colors, or codes. Detection systems in a receiving unitsensitive to particular radiations may be arranged accordingly tocombine or separate various signals as desired. This may again beillustrated with a set of red, blue and green phosphors. Separatecontrol grid signals are applied to each color at the same time. Thevarious colors, though transmitted together, are distinguished at thereceiver by individual photocells sensitive to only one color, eitherred, blue or green. Thus, three independent signals are projectedsimultaneously and separated into three different channels at thereceiver. Similarly, the colors may be programmed or multiplexed in apreset sequence, with only one color being transmitted at a time. Theinformation is then reassembled at the receiver by properly coordinatingthe red, blue and green photosensitive units.

Fig. 2 shows another version of the instant invention wherein controlgrids 48, 5t and 52 take the form of arcuate portions of a cylinder. Thephosphor sections 54, 56 and 58 take the form of arcuate sections of acone, respective grids and phosphors being arranged radially about thecathode 22 and separated by longitudinal partitions 60, 62 and 64, whichin this configuration need not be transparent. The manner of operationis otherwise the same as heretofore described.

Fig. 3 represents a cylindrical outer container configuration whereinthe inner surface of one half of the longitudinal cylinder 110 forms thephosphor coated anode and light is emitted transversely through atransparent longitudinal faceplate 112 which forms the other half of thecylinder. This differs from the conical structure of Fig. l, in thatlight is projected through the side of the cylinder rather than out ofthe end of the cone. Again, multiple grid and phosphor sections may bepositioned to occupy portions of the length of the envelope or arcuatestrips of the periphery of the cylinder. In this instance, thelongitudinal partition plates would have to be transparent while thecircular plates need not be.

in Fig. 3 the end of the cylinder has been cut away'to show the metalliclayer 114 and a single phosphor coating 116 deposited on the first orrear half of cylinder 110. Only one half of cathode 122 is utilized inthis configuration and only the useful surface need be coated withelectron emissive material. Grid 128 is also positioned to controlelectron flow from the proper portion of the cathode. The transparentfaceplate 112 may take.

the form of a fiat rectangular or planar sheet extending for the lengthof the cylinder. Correspondingly, the cathode may be constructed in theform of one half a cylinder, having a fiat side along its length. Thephosphor coated anode and the faceplate may occupy various arcuateportions of the periphery of the cylinder and extend for variouslengths.

Fig. 4 illustrates another control grid arrangement 66 in the form of ahelix, which may be employed to supply modulating signals. An additionalaccelerating grid 68 may be placed around the control grid and cathodeto obtain even greater light emission by increasing and speeding theflow of electrons toward the anode. iOther components remain unchanged.

The concentric arrangement of anode and cathode of the instant inventionprovides larger emissive surfaces and develops greater light output thanavailable from previous phosphorescent devices. The present structurealso avoids the frequency and voltage limitations inherent in prior artgas tube devices. The lengthwise controlgrid configuration adjacent toand positioned about the cathode furnishes a large area for improvedregulation of electron flow.

Modifications of the invention may employ a metallic shell in place ofthe glass envelope and conductive coating. In this case, the shell wouldact as the anode. To facilitate physical handling of the device, theanode may be placed at ground potential. Large areas of metal would havethe advantage of providing efficient cooling surfaces and preventburning of the phosphors. The envelope may have other cross sectionalconfigurations such as rectangular, elliptical, parabolic, etc. Theanode and cathode surfaces and the control grid may alsotake variousshapes, forms, or curvatures other than those described. For productionof multiple radiations, separate cathodes, heaters, and anodes may beutilized. In addition, special purpose faceplates may beemployed to meetindividual requirements.

The described invention may be used in a number of ways. Firstly, it maybe employed for photographic, stroboscopic, and other light flashingpurposes, and will provide a highly luminous pulsed or modulated lightat higher repetition rates than heretofore possible. Secondly, the lightproduced by this invention may be modulated at any given frequency, andby tuning the receiving unit to the modulation frequency, the light orpulses thereof may be distinguished, even in bright daylight. Thirdly,information applied to the various control grids will produce lightpulses of different colors or radiations, which will correspond to aparticular combination of. input signals. Fourthly, the describedinvention may' be used in short range visual communication systems wherein it is desirable to avoid interception of radio', signals or codedinformation. The use of intensity and/or fre quency modulated light maybe useful for direct communication, with highly directional sensitivelight responsive devices such as photocells being employed as sensingelements in the receiving unit to detect and reconvert the modulatedlight into electrical information.

While only a single embodiment of the invention has been indicated, itwill be apparent that the invention is not limited to the exact forms oruse illustrated and that many variations may be made in the particulardesign and configuration without departing from the scope of theinvention, as set forth in the appended claims.

What is claimed is:

l. A light source of high luminosity comprising: an outer containerhaving a plurality of separate adjoining peripheral surfaces, each saidsurface having a different light emission property; a cathode locatedaxially within said container; means for causing electron emission fromsaid cathode; a control grid adjacent to and encircling said cathode;means causing a first portion of said container to act as an anode forattracting and collecting said electrons; at phosphor coating occupyingat least one of said surfaces of said container, said coating emittinglight upon said collection of said electrons; and means to direct saidlight, said means comprising said surfaces of said container and atransparent faceplate through which said light is directed, saidfaceplate enclosing a second portion of said container.

2. The device of claim 1 wherein said outer container is in the form ofa cylinder.

3. The device of claim 2 wherein said light emitting phosphor occupies afirst peripheral portion extending along the length of said cylinder.

4. The device of claim 3 wherein said transparent faceplate occupies asecond peripheral portion extending along the length of said cylinder.

5. The device of claim 2 wherein said transparent faceplate is planarand extends along the length of said cylinder.

6. The device of claim 1 wherein said outer container is funnel shaped.

7. The device of claim 6 wherein said transparent faceplate encloses thewide end of said funnel shaped container.

8. A light source comprising: containing means having a plurality ofseparate adjoining surfaces disposed about the inner periphery of saidcontaining means, each said surface having individually distinct lightemission characteristics; longitudinally disposed means within saidcontaining means for radially emitting electrons; means for controllingthe flow of said electrons; means circumjacent said electron emittingmeans positioned radially outward of said control means for collectingsaid electrons; means adjacent said collecting means for emitting lightupon said collection of said electrons, said light emitting meansoccupying at least one of said surfaces of said containing means; andmeans for directing said light.

9. A source of light having large emissive surface areas comprising: anouter envelope structure; means for emitting electrons radially aboutthe longitudinal axis of said structure, said means comprising anaxially located tubular cathode having an electron emissive layer on thesurface thereof and heater filaments within said cathode; means forcontrolling the flow of said electrons, said means comprising a controlgrid circumjacent to to control said electrons; means for attracting andcollecting said electrons, said means comprising said envelope structuresurrounding said axial cathode and control grid; means for emitting aplurality of light ratiations upon said collection of said electrons,each said radiation having a discrete spectral composition, said meanscomprising a plurality of adjoining separate and distinct phosphorcoatings on the inner surface of said surrounding envelope structure;and means for directing said light, said means comprising said envelopestructure and a transparent faceplate through which said light isdirected, said faceplate enclosing a portion of said envelope.

10. The device of claim 9 wherein said means for controlling the flow ofsaid electrons comprises a plurality of control grids. I

11. The device of claim 10 wherein said plurality of control grids areindividually positioned circumjacent said cathode in a longitudinalarrangement, each said grid encircling a portion of the length of saidcathode.

12. The device of claim 10 wherein said plurality of control grids areindividually positioned about said cathode in a radial arrangement, eachsaid grid being adjacent to a peripheral portion of said cathode andextending said cathode, whereby modulating signals may be applied forsubstantially the full length of said cathode.

13. The device of claim 9 wherein said plurality of phosphor coatingsare arranged in separate peripheral strips, each said strip encircling aportion of the length of said envelope structure.

14. The device of'claim 9 wherein said plurality of phosphor coatingsare arranged in longitudinal strips, each said strip covering a portionof the periphery of said envelope structure.

15. The device of claim 9 wherein said envelope is partitioned into aplurality of sections, each section having an individual control gridand a coacting individual phosphor coating, whereby each said gridcontrols electron flow only to said coacting phosphor coating within thesame said section, each said section being capable of emitting lightindependently of other said sections.

16. The device of claim 15 wherein said plurality of sections havingsaid individual control grids and coacting phosphor coatings arearranged to occupy adjacent peripheral areas along the longitudinal axisof said envelope.

17. The device of claim 15 wherein said plurality of sections havingsaid individual control grids and coacting phosphor coatings arearranged radially about the longitudinal axis of said envelope eachoccupying an angular sector of the periphery of said envelope.

18. The device of claim 9 wherein said envelope is funnel shaped andsaid faceplate encloses the wide end of said envelope.

19. The device of claim 9 wherein said envelope is in the shape of acylinder and said faceplate encloses a peripheral portion of saidcylinder. n,

20. The device of claim 19 wherein said faceplate is planar.

References Cited in the file of this patent UNITED STATES PATENTS2,119,309 Batchelor May 31, 1938 2,222,668 Knoll Nov. 26, 1940 2,392,161Leverenz Jan. 1, 1946 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No, 2,907,909 October 6, 1959' Walter Frank Kazulc Itis hereby certified that error appears in the -printed specification ofthe above numbered patent requiring correction and that the said LettersPatent should read as corrected below.

Column 2, lines 39 and 40, for "homogeneous" read homogeneously column5, line 47, after "means" insert cir'cumjacent said electron emittingmeans lines 48 and 49, after "means" strike out "circumjacent saidelectron emitting means"; column 6, line 4, for "ratiations" readradiations Signed and sealed this 22nd day of March 1960,

(SEAL) Attest:

KARL H0 AXLINE Attesting Oflicer ROBERT C. WATSON Commissioner ofPatents

